The grades on a history midterm at Almond are normally distributed with $\mu = 66$ and $\sigma = 4.5$. Gabriela earned a $70$ on the exam. Find the z-score for Gabriela's exam grade. Round to two decimal places.
A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Gabriela's exam grade by subtracting the mean $(\mu)$ from her grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{70 - {66}}{{4.5}}} $ ${ z \approx 0.89}$ The z-score is $0.89$. In other words, Gabriela's score was $0.89$ standard deviations above the mean.